1999 Honda Civic car hesitating at low revs

Hi, I have a honda civic 1999 1.6 dohc vti. I am in the uk. My problem is the car is hestiating at low revs, if you put your foot down it just hesitates and cut's off, it's fine at high rev range but in lower rev's it is constant problem, I was driving along and slowed down for the lights, as I went to take off again the car hesitates and cut's off sometimes it starts back up again straight away and sometime it takes 5-10 mins to start back up, this is very frustrated and making the car un-driveable. When the car hestiates the rev's drop down to zero. Also before this problem the temp gauage would go from midway (after being warmed up fpr long enough) to cold but the heating was still warm, since the hesitating problem started the temp gauage does not do this anymore.

i took it to the garage and they could not find any obvious problems, so the put the diagnostics upto to and come up with trouble code 64, the mechanic says the civic codes only go upto 40, so he took them as being, 6 & 4, one being for a temp sensor and one for the map sensor (very expensive). So he changed the temp sensor, it was fine for a little while but the problem is still there, it hesitates at low rev's and sometimes makes a dodgy cranky noise when it's cutting out.

any idea what I could be, the mechanic goes it could be down to the map sensor now (but it's  £180 and im only going to get that if it's definately is the map sesnor) I have looked on forums and peeple are saying it could be the fuel fillter, inlet manifold bulit up with carbon deposits, distributor or even an altenator surging from high to low.

pls advise as this is getting very frsutarting